西藏冈底斯带西部达雄岩体的岩石成因:锆石U-Pb年龄和Hf同位素约束
Petrogenesis of Daxiong pluton in western Gangdese, Tibet: zircon U-Pb dating and Hf isotopic constraints
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摘要: 对出露于冈底斯西部地区措勤北部达瓦错东侧的达雄岩体进行了锆石U-Pb定年、全岩主量元素、微量元素、Sr-Nd同位素和锆石Hf同位素研究,以约束其岩石成因.达雄岩体的主体岩性为花岗闪长岩,其中发育大量闪长质包体.花岗闪长岩的锆石LA-ICP MS年龄为107±1Ma,该年龄代表了岩体结晶年龄.花岗闪长岩锆石εNd(t)值变化于-1.0～3.0,两阶段模式年龄变化于974～1226Ma.花岗闪长岩富硅(SiO2=70.65%～71.10%),富钙(CaO=3.21%～3.26%)、贫钾(K2O=2.81%～2.99%)、低P2O5(0.09%),铝饱和指数(A/CNK)为1.01～1.02,属于偏铝质花岗岩或弱过铝质花岗岩.闪长质包体SiO2含量为57.84%,与寄主岩相比,闪长质包体更富CaO、MgO、TFe2O3和TiO2.花岗闪长岩和闪长质包体均属中钾钙碱性系列,εNd(t)值分别为-4.6和-3.2,两阶段模式年龄(tDM2)相近(分别为1277Ma和1166Ma),并与锆石Hf同位素模式年龄一致.岩相学、年代学和地球化学研究表明闪长质包体可能是由岩浆混合作用形成的镁铁质微粒包体.我们的初步研究成果似乎表明,冈底斯中西部地区在早白垩世晚期(～110Ma)很可能存在一次重要的岩浆混合作用,这一初步认识对研究冈底斯中北部地区规模宏大的白垩纪岩浆作用的深部动力学过程具有重要意义.
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[1] Allen CM. 1991. Local equilibrium of mafic enclaves and granitoids of the Turtle pluton, southeast California: Mineral, chemical, and isotopic evidence. American Mineralogist, 76:574 - 588
[2] Anderson T. 2002. Correction of common lead in U-Pb analyses that do not report ^204 Pb. Chemical Geology, 192 : 59 - 79
[3] Beloisova BA, Griffin WL and O\\'Reilly SY. 2006. Zircon crystal morphology, trace element signatures and Hf isotope compositon as a tool for petrogenetic modeling: Examples from Eastern Australian granitoids. Journal of Petrology, 47 : 329 - 353
[4] De La Roche H, Leterrier J, Grande Claude P and Marchal M. 1980. A classification of volcanic and plutonic rocks using R1-R2 diagrams and major element analysis-its relationships and current nomenclature. Chemical Geology, 29 : 183 - 210
[5] Deng JF, Zhao HL, Mo XX, Wu ZX and Lao ZH. 1996. Continental Roots-Plume Tectonics of China Key to the Continental Dynamics. Beijing: Geological Publishing Houses, 1 -82
[6] Didier J and Barbarin B. 1991. Enclave and Granite Petrology. Elsevier: Amsterdam, 1 -625
[7] Dong GC, Mo XX, Zhao ZD, Guo TY, Wang LL and Cheng T. 2005. Geochronologic constraints on the magmatic underplating of the Gangdese Belt in the India-Eurasia Collision: Evidence of SHRIMP Ⅱ zircon U-Pb dating. Acta Geologica Sinica, 79 (6) : 801 -808
[8] Dong GC, Mo XX, Zhao ZD, Zhu DC, Wang LL, Chen T and Li B. 2006. Magma mixing in middle part of Gandise magma belt: Evidences from granitoid complex. Acta Petrologica Sinica, 22 (4) : 835 -844
[9] Griffin WL, Wang X, Jackson SE, Pearson NJ and O\\'Reilly SY. 2002. Zircon geochemistry and magma mixing, SE China: in-situ analysis of Hf isotopes, Tonglu and Pingtan igneous complexes. Lithos, 61 :237 -269
[10] Holden P, Halliday AN and Stephes WE. 1987. Neodymium and strontium isotope content of microdiorite enclaves points to mantle input to granitoid production. Nature, 330:53 - 162
[11] Jiang W, Mo XX, Zhao CH, Guo TY and Zhang SQ. 1998. Granodiorites and their marie microgranular enclaves from the Gangdise granite belt of the Qinghai-Xizang Plateau. Tethyan Geology, 22:90-95
[12] Jiang W, Mo XX, Zhao CH, Guo TY and Zhang SQ. 1999. Geochemistry of granitoid and its mafic microgranular enclave in Gangdise belt, Qinhai-Xizang plateau. Acta Petrologica Sinica, 15 (1) : 89- 97
[13] Jin CW. 1986. Enclaves in Qushui granite batholith, Lhasa, Tibet. Acta Petrologica Sinica, 2 (2): 23 -32
[14] Jin ZM and Gao S. 1996. Underplating and its significance for geodynamics in the evolution of the crust-mantle. Information of Science and Technology in Geology, 15 (2) : 1 -7
[15] Lesher CE. 1990. Decoupling of chemical and isotopic exchange during magma mixing. Nature, 344:235 -237
[16] Li CN. 2002. Comment on the magma mixing and their research. Geological Science and Technology Information, 21 (4) : 49 -54
[17] Ludwig KR. 2003. Isoplot 3.0- A geochronological toolkit for Microsoft Excel. Berkeley Geochronology Center, Spec. Pub. , (4) : 1 - 70
[18] Maniar PD and Piccolli PM. 1989. Tectonic discrimination of granitoid. Geol. Soc. Am. Bull., 101:635-643
[19] Mo XX, Dang GC, Zhao ZD, Zhou S, Wang LL, Qiu RZ and Zhang FQ. 2005. Spatial and Temporal Distribution and Characteristics of Granitoids in the Gangdese, Tibet and implication for Crustal Growth and Evolution. Geological Journal of China Universities, 11 ( 3 ) : 281 -290
[20] Mo XX, Luo ZH, Xiao QH et al. 2002. Evidence of magma mixing in granitoids plutons and the way of investigation. In: Xiao QH, Deng JF, Ma DQ et al. (eds.). The Ways of Investigation on Graitoids. Beijing: Geology Publishing House, 53 -71
[21] Pearce JA, Harris NBW and Tindle AG. 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25 : 956 - 983
[22] Rudnick RL and Gao S. 2003. Composition of the continental crust. In: Rudnick RL (ed.). The Crust, 1 -64, Treaties on Geochemistry, v. 3. Oxford: Elsevier Pergamon
[23] Sun SS and McDonough WF. 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In: Saunders AD and Norry MJ (eds.). Magmatism in the Ocena Basins. Geological Society Special Publication, 42:313 -345
[24] Tan FW and Liu CJ. 1992. Preliminary study of the enclaves in Gangdese batholith, Tibet. Mineralogy and Petrology, 12 ( 2 ) : 21 - 27
[25] Tu GZ, Zhang YQ, Zhao ZH and Wang ZG. 1981. Characteristics and Evolution of granitoids of South Tibet. Geochimica, ( 1 ) : 1 -7
[26] Vervoot JD and Blichert-Toft J. 1999. Evolution of the depleted mantle: Hf isotope evidence from juvenile rocks through time. Geochimica et Cosmochimica Acta, 63 : 533 - 556
[27] Wang T. 2000. Origin of hybrid granitoids and the implications for continental dynamics. Acta Petrologica Sinica, 16 (2) : 161 - 168
[28] Wu FY, Li XH, Zheng YF and Gao S. 2007. Lu-Hf isotopic systemtics and their applications in petrology. Acta Petrologica Sinica, 23 (2) : 185 -220
[29] Wu FY, Yang YH, Xie LW, Yang JH and Xu P. 2006. Hf isotopic compositions of the standand zircons and baddeleyites used in U-Pb geochronology. Chemical Geology, 234:105 -126
[30] Wu XL and Chen ZH. 2005. Geochemistry and genesis of the Nyixung rock body in northern Tibet. Geology in China, 32( 1 ) : 122 - 127
[31] Wu YB and Zheng YF. 2004. Genesis of zircon and its constrains on interpretation of U-Pb age. Chinese Science Bullutin, 49 (16): 1589 - 1604
[32] Xu P, Wu FY, Xie LW and Yang YH. 2004. Hf isotope of U-Pb dating standard zircon. Chinese Science Bullutin, 49 (14) : 1403 - 1413
[33] Yang JH, Wu FY, Chung SL, Simon AW and Chu MF. 2004. Multiple source for the origin of granites: Geochemical and Nd/Sr isotopic evidence from the Gudaoling granite and its mafic enclaves, northeast China. Geochimica et Cosmochimica Acta, 68(21 ) : 4469 -4483
[34] Yang JH, Wu FY, Chung SL, Wilde SA and Chu MF. 2006. A hybrid origin for the Qianshan A-type granite, northeast Chlna: Geochemical and Sr-Nd-Hf isotopic evidence. Lithos, 89:89 -106
[35] Yang JH, Wu FY, Wilde SA, Xie LW, Yang YH and Liu XM. 2007. Trace magma mixing in granite genesis: in-situ U-Pb dating and Hfisotope analysis of zircons. Contributions to Mineralogy and Petrology, 153 : 177 - 190
[36] Yang JH, Wu FY, Xie LW and Liu XM. 2007. Petrogenesis and tectonic implications of Kuangdonggou syenites in the Liaodong Peninsula, east North China Craton: Constraints from in-situ zircon U-Pb ages and Hf isotopes. Acta Petrologica Sinica, 23 ( 2 ) : 263 - 276
[37] Yuan HL, Gao S, Liu XM, Li HM, Gunther D and Wu FY. 2004. Accurate U-Pb age and trace element dterminations of zircon by laser ablation-inductively coupled plasma mass spectrometry. Geostandards Newsletter, 28:353 -370
[38] Zhu DC, Pan GT, Mo XX, Liao ZL, Zhao ZD, Dong GC and Zhou CY. 2006. Late Jurassic-Early Cretaceous geodynamic setting in middlenorthern Gangdese: New insights from volcanic rocks. Acta Petrologica Sinica, 22 ( 3 ) : 534 - 546
[39] Zhu DC, Pan GT, Wang LQ, Mo XX, Zhao ZD, Zhou CY, Liao ZL, Dong GC and Yuan SH. 2008. Spatial and Temporal variations of the Mesozoic magmatic rocks in the Gangdese Belt, Tibet and discussion on geodynamic setting-related issues involved in their generation. Geological Bulletin of China, 27 (9): in press
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